The overall objective of this proposal is to describe the learning of preferences for food odors by human infants just beginning to ingest semi- solid foods between 4- and 6-months-of-age. This is a special and important period in the development of feeding behavior and possibly for learning odor preferences. The focus is on processes involved in the formation of preferences for new food odors and on identification of their associated nutritional value. Systematic data on this general issue exists at post weaning ages (2- to 5-years-old) but not in infants who are just beginning to eat solid food. The proposed research addresses this gap in knowledge. The specific aims are to evaluate: 1) the role of associative learning in the infant's first preferences for food odors (experiments 1 and 2). 2) the importance of mother-infant interactions in the infant's acquisition of preferences for food odors (Experiment 3). 3) the role of food cues such as sweetness and caloric benefits in the conditioning of odor preferences (Experiment 4). We will test infants in a discrimination procedure consisting of alternately placing drops of banana- or lemon-like odorant solutions on their tongue, generally as if spoon feeding the infant. One odorant will be paired with sweetness, maternal interaction or caloric benefits and the other odorant will be presented without such stimulation. Behavioral measures which will be used to quantify infants' preferences for odorants are oral and facial movements and intake of odorant solutions. We will assess infants retention of odor preferences after a 24 hour delay. The results will elucidate learning mechanisms of ingestion of a novel food by infants during their earliest experiences semi-solid foods. The findings would also provide a baseline against which to identify infants at risk for early nutritional problems.